Device for regulating positive end expiratory pressure

ABSTRACT

A device for regulating the positive end expiratory pressure of a patient under anesthesia is disclosed. The device is suitable for insertion into an anesthesia circuit and comprises an enclosed container separated into two chambers by a wall terminating below the top of the container. A liquid contained in the container is movable between the two chambers by passing over the wall when the container is tilted. The container top has two openings through which two tubes project. A long tube extends downwardly and terminates at the bottom of one chamber and a short tube terminates near the top of the container. Air exhausted by the patient passes downwardly through the long tube and bubbles upwardly through the liquid located in the associated chamber of the container. The air, after bubbling upwardly, exhausts through the short tube. The level of liquid through which the exhausted air bubbles creates a resistance which regulates positive end expiratory pressure.

United States Patent 1191 Bollinger 1451 Mar. 11, 1975 DEVICE FOR REGULATING POSITIVE END EXPIRATORY PRESSURE [76] Inventor: Charles W. Bollinger, 10531 Nottingham Rd., Edmonds, Wash. 98020 22 Filed: Oct. 17, 1973 21 App]. No.: 407,140

[52] US. Cl 128/188, 261/124, 215/6,

128/1423 [51] Int. Cl A61m 17/00 [58] Field of Search 128/188, 186, 187, 194,

[56] References Cited UNITED STATES PATENTS 3,661,143 5/1972 Henkin 128/2 F 3,699,815 10/1972 Holbrook 128/2 F Primary Examiner-Richard A. Gaudet Assistant Examiner-Henry J. Recla Attorney, Agent, or FirmChristensen, OConnor,

Garrison & Havelka [57] ABSTRACT A device for regulating the positive end expiratory pressure of a patient under anesthesia is disclosed. The device is suitable for insertion into an anesthesia circuit and comprises an enclosed container separated into two chambers by a wall terminating below the top of the container. A liquid contained in the container is movable between the two chambers by passing over the wall when the container is tilted. The container top has two openings through which two tubes project. A long tube extends downwardly and terminates at the bottom of one chamber and a short tube terminates near the top of the container. Air exhausted by the patient passes downwardly through the long tube and bubbles upwardly through the liquid located in the associated chamber of the container. The air, after bub bling upwardly, exhausts through the short tube. The level of liquid through which the exhausted air bubbles creates a resistance which regulates positive end expiratory pressure.

8 Claims, 4 Drawing Figures DEVICE FOR REGULATING POSITIVE END EXPIRATORY PRESSURE BACKGROUND OF THE INVENTION This invention is directed to regulating devices for use in medical anesthesia apparatus and, more particularly, to devices for regulating positive end expiratory pressure.

Certain pulmonary diseases are characterized by premature closure of the bronchi on expiration. This premature closure prevents air from leaving the lungs of the patient. A conscious patient can easily overcome this problem by, for example, pursing his lips on expiration. This action creates a high resistance which prevents premature closure of the bronchi. However, a patent who is under anesthesia cannot take this action, because he is unconscious. Normally, such a patient exhales into a tube nearly the size of the trachea which graduates into even larger tubes. The whole system creates a low resistance when exactly the counter effect (high resistance) is needed.

In the past, some anesthesiologists have created a resistance to expiratory air flow by passing expiration air through a predetermined number of centimeters of water. While these devices have been somewhat satisfactory, they have a variety of disadvantages. For example, in general, these devices have been created on a as needed basis. Thus, they have been crudely constructed, cumbersome, and have been difficult to sterilize. Further, they have not provided the control necessary to m'ake them useful in a wide variety of situations. For example, the resistance created by these devices has been difficult to change without loss of sterilization.

Therefore, it is an object of this invention to provide a device for regulating positive end expiratory pressure.

It is also an object of this invention to provide a device for regulating positive end expiratory pressure which is uncomplicated and suitable for ready insertion into an anesthesia circuit.

It is a still further object of this invention to provide a device for regulating positive end expiratory pressure which is inexpensive to manufacture, easy to sterilize and maintain sterilized, and suitable for widespread use under varying circumstances where different or changeable resistances to expiratory air are desired.

SUMMARY OF THE INVENTION In accordance with principles of this invention, a device for regulating the positive end expiratory pressure of a patient is provided. The device comprises an enclosed container suitable for holding a liquid. A wall separates the container into two chambers and is formed such that the liquid contained in the container can be easily moved from one chamber to the other chamber. Two tubes extend downwardly through the top of the container. One tube terminates near the bottom of one chamber, and the other tube terminates near the top of the container. Air exhausted by the patient passes through the tube that terminates at the bottom of the one chamber and bubbles up through the liquid located in that chamber. The exhaust air then leaves the device through the other tube.

In accordance with further principles of this invention, the wall is a solid wall which terminates beneath the top of the container. The thusly formed wall allows liquid to pass from one chamber ofthe container to the other chamber when the container is tilted. In accordance with other principles of this invention, the chamber containing the liquid through which the gases bubble has graduations associated with it, so that the level of liquid contained in that chamber can be readily determined.

In accordance with other principles of this invention, a split-T connector structure also forms part of the invention. The split-T includes a center wall that prevents communication between the ends of the split-T. One leg of the split-T is connected to one tube, and the other leg is connected to the other tube. The ends of the split-T are suitable for connecting the inventive device into an anesthesia circuit.

It will be appreciated from the foregoing brief sum mary that a new and improved apparatus for regulating positive end expiratory pressure suitable for use in an anesthesia circuit is provided by the invention. The uncomplicated split-T allows the device to easily inserted into existing anesthesia circuit equipment, at the point where expiration gases from the patient flow back to the equipment. In addition, the device is formed such that the height ofa liquid, which controls the resistance applied to the expiratory gases, is easily controlled by moving the liquid from one chamber of a container to another chamber. Thus, not only is it easy to control the initial resistance applied to exhaust air, but such resistance is easily changed as necessary, such as during an operation, for example. All that need be done is to tilt the container through an angle of or so in order for liquid to flow from one chamber to the other chamber. Finally, the entire structure is formed such that it can be easily sterilized and sold as a single unit ready for direct insertion into an anesthesia circuit.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing objects and many of the attendant advantages ofthis invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description when taken in conjunction with the accompanying drawings. wherein:

FIG. 1 is a block diagram illustrating an anesthesia circuit;

FIG. 2 is a schematic diagram illustrating, in crosssection,.the apparatus of the invention inserted into an anesthesia circuit;

FIG. 3 is a pictorial diagram partially broken away illustrating a preferred embodiment of a container formed in accordance with the invention; and,

FIG. 4 is a pictorial diagram, partially in section, illustrating a split-T suitable for connecting the container illustrated in FIG. 3 into an anesthesia circuit,

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a pictorial diagram illustrating, in generalized form, a prior art closed circuit anesthesia circuit 11. The anesthesia circuit 11 comprises a mask 13 adapted to enclose the nose and mouth of a patient 15. The mask 13 includes one terminal 17 suitable for receiving an inhalation tube 19 and a second terminal 21 suitable for receiving an expiration tube 23. The expiration tube 23 is connected to a first one-way valve 25 which allows gases to pass from the expiration tube to an exhaust tube 27. Attached to the one-way valve 25 is a reservoir bag 29, as is well known in the art. The exhaust tube terminates at an absorber 33. The absorber 33 houses a suitable carbon dioxide removing material, such as a soda-lime mixture, for example. After passing through the absorber 33, exhaust air is mixed with external gases received through an inlet 35 formed in an input tube 37. The inlet tube 37 is connected to a second one-way valve 39. The output of the second one-way valve 39 is connected to the inhalation tube 19.

As is well known to those skilled in the anesthesiology art, the patient receives oxygen and anesthesia gases via the inhalation tube 19 and exhausts air and excess anesthesia gases through the expiration tube 23. The one-way valves force gases to flow in the desired (illustrated) direction. After exhalation, the air passes through the carbon dioxide absorber where carbon dioxide is removed. The thusly cleansed air is mixed with anesthesia gas, as well as additional oxygen, and returned to the patient.

One of the problems with closed circuit anesthesia systems of the type illustrated in FIG. 1 is that they are not suitable for use by patients with pulmonary diseases characterized by premature closure of the bronchi. Moreover, non-rebreathing anesthesia systems present the same problem. More specifically, premature closure of the bronchi on expiration prevents air from leaving the lungs. Normally, a conscious patient having a disease of this nature can easily overcome this problem, by, for example, pursing his lips on expiration. However, a patient who is under anesthesia cannot take this action. His exhalation into the expiration tube 23 (which normally is larger than his trachea) in effect is an exhalation into a low resistance region. Contrawise, exactly the counter effect (high resistance) is needed to overcome the premature closure of the bronchi problem.

This invention provides a device for use in an anesthesia circuit of the type illustrated in FIG. 1 and in other types of both closed and non-rebreathing anesthesia circuits that create ahigh resistance to exhaust air flow and, thus, prevent premature closure of the bronchi. More specifically, the invention provides a device for insertion into the expiratory circuit by breaking the connection between the tube 23 and valve 25 and inserting a split-T connection therebetween. The device causes the expiration air to pass through a liquid that creates a high resistance to expiration air flow.

FIG. 2 is a schematic diagram illustrating a preferred embodiment of the invention. The expiration tube 23 is removed from the input terminal of valve 25. Inserted in the thusly created opening is a split-T 41. The split-T has two ends 42 and 44 separated by a wall 43, and two legs 45 and 47. Preferably, the split-T is formed such that one end 42 is designated the input. The input end is in the form of a male connector and the proximal end of the expiration tube 23 acts as a female connector. Contrawise, the other end 44 of the split-T 41 is designated the output and is in the form of a female connector. The distal terminal of the expiration valve 25, thus, acts as a male connector. It should be noted, and will be appreciated by those skilled in the art that FIG. 2 only illustrates one type of device for connecting the apparatus of the invention into an anesthesia circuit and that a wide variety of other types of connection devices can be used, as desired.

One leg 45 of the split-T is associated with the input 42 and the other leg 47 is'associated with the output 44. The input leg 45 is attached to a long tube 51, and the output leg is attached to a short tube 53. The long tube 51 passes downwardly through an opening 55 formed in the top 57 of an enclosed container 59..The short tube 53 passes downwardly through a second opening 61 also formed in the top 57 of the container 59.

The container 59, as illustrated in FIGS. 2 and 3, is separated into two chambers 65 and 69 by a wall 63. The long tube 51 passes downwardly through the first chamber 65 and terminates at the bottom of the chamber. Preferably, the long tube 51 is attached to the bot tom of the first chamber and includes a plurality of apertures 67 located near its bottom which communicate between the interior of the long tube 51 and the interior of the chamber 65. Also, preferably the apertures 67 do not in and of themselves cause a resistance to the passage of exhaust air. Thus the cross-sectional area of the apertures 67 is preferably equal to or greater than the cross-sectional area of the long tube 51, or at least equal to or greater than the cross-sectional area of any connector or tubes in the system. The short tube 53 terminates near the top 57 of the container 59, preferably above the other chamber 69.

A liquid 71 is free to flow between the two chambers when the container 59 is tilted through an angle of 180 or so. In this manner, the level. of the liquid in the first chamber is easily controlled-the liquid in the second chamber acting as a reservoir for the liquid.

While the long and short tubes 51 anti 53 have been illustrated for convenience in FIG. 2 as being relatively short, it will be appreciated that these tubes should be long enough to allow the container to be easily tilted to the degree necessary. Preferably, the container 59 is translucent. Graduations 73 are marked on the container 59 adjacent the first chamber 65 so that the level of the liquid 71 in the first chamber 65 can readily be read.

In operation, exhalation gases from the patient 15 are received at the input side of the split-T and pass downwardly through the long tube 51. The gases pass through the apertures 67 in the long tube 51 and bubble upwardly through the liquid 71 located in the first chamber 65. After bubbling through the liquid 71, the expiration gases exit from the container via the short tube 53. These gases then return to the anesthesia circuit via the output side of the split-T. The level of the liquid in the first chamber 65 controls the amount of resistance applied to the expiration gases. Since this level is easily controlled both prior to and during an operation, premature closure of the bronchi is easily prevented by the use of the invention.

It will be appreciated from the foregoing description that a device for regulating positive end expiratory pressure is provided by the invention. The device is inexpensive to manufacture, only requiring a split-T, a suitable container and long and short tubes. Not only is the device easily manufactured, it is also easily sterilized and maintained sterile until used. Further, the invention provides easy control of the amount of resistance applied to expiration gases. While sterile water is the preferred liquid used by the invention, other liquids, as desired, can be used.

While a preferred embodiment of the invention has been illustrated and described, it will be appreciated by those skilled in the art and others that various changes can be made therein without departing from the spirit and scope of the invention. For example, while uncomplicated tubing connector means have been illustrated and described, it will be appreciated that other types of connectors can be utilized as long as they do not restrict expiration gases by creating a narrow uncontrolled region through which expiration gases must pass. Moreover, while the container 59 has been illustrated as having a separate top 57, it will be appreciated that it can be formed as a unitary structure, if desired. Hence, the invention can be practiced otherwise than specifically described herein.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A device for regulating positive end expiratory pressure comprising:

an enclosed container divided into two chambers by a wall, said wall allowing a liquid housed in said container to be moved between said two chambers when said container is tilted in a predetermined manner from a normal upright position; liquid housed in said chambers of said container;

a first tube extending into one of said chambers, said first tube being attached to the bottom of said one of said chambers and including apertures located adjacent the end attached to the bottom of one of said chambers, said apertures communicating between the interior of said first tube and the interior of said one of said chambers; and,

a second tube extending into said container so as to have one end terminate above said liquid in said chambers,

2. A device for regulating positive end expiratory pressure as claimed in claim 1, including a connection means connected to the other ends of said tubes which prevents communication between the other ends of said tubes and is adapted for connecting the other ends of said tubes into an anesthesia circuit.

3. A device for regulating positive end expiratory pressure as claimedin claim 2, wherein said container is enclosed by a top and wherein said first and second tubes pass through apertures in said top.

4. A device for regulating positive end expiratory pressure as claimed in claim 3, wherein said wall terminates below the top of said container so as to provide an aperture between the top of said container and the top of said wall.

5. A device for regulating positive end expiratory pressure as claimed in claim 4, wherein said container is translucent and including graduations associated with said one of said chambers whereby said liquid level in said one of said chambers can be easily determined.

6. A device for regulating positive end expiratory pressure as claimed in claim 5, wherein said attachment means is a split-T having an input end, an output end and two legs, one leg being associated with said input end and the other being associated with said output end, the leg associated with said input end being connected to said first tube and the leg associated with said output end being connected to said second tube, said split-T including a wall separating said ends from one another.

7. A device for regulating positive end expiratory pressure as claimed in claim 1, wherein said wall terminates below the top of said container so as to provide an aperture between the top of said container and the top of said wall.

8. A device for regulating positive end expiratory pressure as claimed in claim 1, wherein said container is enclosed by a top and wherein said first and second tubes pass through apertures in said top. 

1. A device for regulating positive end expiratory pressure comprising: an enclosed container divided into two chambers by a wall, said wAll allowing a liquid housed in said container to be moved between said two chambers when said container is tilted in a predetermined manner from a normal upright position; a liquid housed in said chambers of said container; a first tube extending into one of said chambers, said first tube being attached to the bottom of said one of said chambers and including apertures located adjacent the end attached to the bottom of one of said chambers, said apertures communicating between the interior of said first tube and the interior of said one of said chambers; and, a second tube extending into said container so as to have one end terminate above said liquid in said chambers.
 1. A device for regulating positive end expiratory pressure comprising: an enclosed container divided into two chambers by a wall, said wAll allowing a liquid housed in said container to be moved between said two chambers when said container is tilted in a predetermined manner from a normal upright position; a liquid housed in said chambers of said container; a first tube extending into one of said chambers, said first tube being attached to the bottom of said one of said chambers and including apertures located adjacent the end attached to the bottom of one of said chambers, said apertures communicating between the interior of said first tube and the interior of said one of said chambers; and, a second tube extending into said container so as to have one end terminate above said liquid in said chambers.
 2. A device for regulating positive end expiratory pressure as claimed in claim 1, including a connection means connected to the other ends of said tubes which prevents communication between the other ends of said tubes and is adapted for connecting the other ends of said tubes into an anesthesia circuit.
 3. A device for regulating positive end expiratory pressure as claimed in claim 2, wherein said container is enclosed by a top and wherein said first and second tubes pass through apertures in said top.
 4. A device for regulating positive end expiratory pressure as claimed in claim 3, wherein said wall terminates below the top of said container so as to provide an aperture between the top of said container and the top of said wall.
 5. A device for regulating positive end expiratory pressure as claimed in claim 4, wherein said container is translucent and including graduations associated with said one of said chambers whereby said liquid level in said one of said chambers can be easily determined.
 6. A device for regulating positive end expiratory pressure as claimed in claim 5, wherein said attachment means is a split-T having an input end, an output end and two legs, one leg being associated with said input end and the other being associated with said output end, the leg associated with said input end being connected to said first tube and the leg associated with said output end being connected to said second tube, said split-T including a wall separating said ends from one another.
 7. A device for regulating positive end expiratory pressure as claimed in claim 1, wherein said wall terminates below the top of said container so as to provide an aperture between the top of said container and the top of said wall. 